Method and system for detecting non-visible vehicles

ABSTRACT

A method for detecting non-visible vehicles in a vehicle&#39;s environment includes screening, by a receiver of a proximity sensor, any incoming proximity signal capable of propagating through the air along a non-linear path. Receiving such an incoming proximity signal and processing the received proximity signal allows for detecting an object that is otherwise not visible to a driver or another type of sensor on a vehicle and warning the driver or an advanced driver-assistance system about the detected object.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/865,930, filed on May 4, 2020, which claims priority to EuropeanPatent Application No. 19177749.9, filed on May 31, 2019.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to systems and methods ofoperating partially and fully-automated or autonomous vehicles.

Such a method is useful especially in the field of human-assisted orautonomous vehicles using sensors for obstacle detection and avoidance,to navigate safely through its environment.

BACKGROUND OF THE DISCLOSURE

Partially and fully-automated or autonomous vehicles have been proposed.

The document US2016/0231746 discloses systems and methods for operatingan automated vehicle such as an autonomous vehicle including anautonomous guidance system, a method of automatically controlling anautonomous vehicle based on electronic messages from roadsideinfrastructure or other-vehicles, a method of automatically controllingan autonomous vehicle based on cellular telephone location information,pulsed LED vehicle-to-vehicle (V2V) communication system, a method andapparatus for controlling an autonomous vehicle, an autonomous vehiclewith unobtrusive sensors, and adaptive cruise control integrated with alane keeping assist system. The systems and methods may use informationfrom radar, LIDAR, a camera or vision/image devices, ultrasonic sensors,and digital map data to determine a route or roadway position andprovide for steering, braking, and acceleration control of a hostvehicle.

However, the systems and methods necessary to control the vehicle can beimproved.

In particular, in certain specific driving situations, such ascrossroads or work area where road work fences are installed, usualsensors like radar and camera cannot detect non-visible vehicles movingin the vehicle's environment and may be towards the vehicle. Moregenerally, non-visible vehicles are caused by obstacles between thesensing vehicle concerned and the non-visible vehicle, such as a parkedcar, a wall, metal plates, road work fences or any other objectobstructing the view between the two vehicles.

Risks of collision increase if an automated vehicle is not able todetect another (non-visible) vehicle on a crossroad or in a work area,reducing the safety of Advanced Driver Assistance System (ADAS) orautonomous driving vehicle.

SUMMARY

A first aspect of the disclosure relates to a method for detectingnon-visible vehicles in a driven vehicle's environment, wherein eachvehicle is equipped with at least one proximity sensor. The methodincludes: screening, by a receiver of the proximity sensor, any incomingproximity signal capable of propagating through the air along anon-linear path; receiving an incoming proximity signal coming from anon-visible vehicle; processing the received proximity signal to detectthe non-visible vehicle; and warning a driver and/or an advanceddriver-assistance system about the detected non-visible vehicle.

By using proximity sensors screening and receiving proximity signalspropagating in the air along a non-linear path, it allows an equippedvehicle to receive these proximity signals despite the presence of someobstacles in between the driven vehicle and another vehicle non-visibleeither for the driver or for the cameras and radar detectors of thedriven vehicle. These proximity signals are capable of propagatingthrough the air along a non-linear path contrary to a light wave comingfrom any light sensor. It therefore allows detection of non-visiblevehicles located behind an obstacle and in turn warning the driver orthe Advanced Driver Assistance System (ADAS) in order to prevent a riskof collision between both vehicles.

Advantageously, the method comprises for each driven vehicle apreliminary step of: emitting, by an emitter of the proximity sensor, aproximity signal capable of propagating through the air along anon-linear path.

In this manner, all equipped driven vehicles are able to be detected byother equipped non-visible driven vehicles. A non-linear path is onewithout reflective surfaces so that a light beam would not be able toreach non-visible vehicles from the driven vehicle.

The emitted proximity signal in some embodiments is a periodic pulse,such as a proximity signal emitted every 100 ms.

Using a periodic pulse reduces the power consumption of the proximitysensor compared to a continuous signal. A frequency of 10 Hz is highenough to allow rapid detection of a non-visible vehicle and to preventa risk of collision.

The at least one proximity sensor in some embodiments is an ultrasonicsensor, the proximity signal is an ultrasonic signal and the screeningstep is a listening step. There may be a plurality of ultrasonic sensorswhich are the parking sensors of the vehicle. The ultrasonic signal canbe a periodic pulse emitted with maximum power of the parking sensor.

The use of ultrasounds prevents any disturbance to the driver and ingeneral to road users. When driving, parking sensors are not used andare therefore available for other purposes such as being used asproximity sensors to detect (non-visible) vehicles in the surroundings.In order to benefit from the maximum range to detect non-visiblevehicle, the ultrasonic signal is emitted with maximum power. Further,the use of ultrasounds does not affect the efficiency of the detectionwhatever the weather conditions are.

Using the parking sensors of existing park assist option enables toimplement the method on the existing automotive fleet of vehiclesequipped with such ultrasonic park assist. Usually, the ultrasonic parkassist uses the same frequency, namely 40 KHz, so that other equippedvehicles can detect the emitted pulse. Compared to the standard usage ofthe ultrasonic park assist, the present method increases (doubles) thedetection distance because one equipped vehicle emits the pulse andanother receives it.

Advantageously, the processing step of the received ultrasonic signalsfurther analyses the Doppler effect to determine the distance and speedof the detected non-visible vehicle.

By analyzing the Doppler effect of the incoming ultrasonic signals, theprocessor can retrieve a variable period of the emitted pulses with willdepend on the distance of the emitter of the non-visible vehicle as wellas its speed.

The ultrasonic signals can be modulated in amplitude and the processingstep further analyses the amplitude modulation to determine any speedvariation of the detected non-visible vehicle.

Modulation of the amplitude of the ultrasonic signal allows to theprocessor to determine if any speed variation of the detectednon-visible vehicle.

The warning step in some embodiments further evaluates and warns about arisk of collision with the detected non-visible vehicle.

Depending on the distance and speed of the detected non-visible vehiclethe warning unit may adapt the warning signal sent to the driver and/orthe ADAS. In case of amplitude modulation of the incoming signals, theprocessor also detects the variation of the speed and the warning unitmay further adapt the warning signal.

The receiver may screen any incoming proximity signal eithercontinuously or when the emitter is not emitting.

To avoid interference between the receiver(s) and the emitter(s) of theproximity sensor(s) of an equipped vehicle, the receiver is inactiveduring emission of the proximity signal.

In some embodiments, each vehicle is equipped with at least one lightsensor and the method includes: detecting visible vehicles in thevehicle's environment by the at least one light sensor; comparing alldetected vehicles by both the light sensor and the proximity sensor; anddetermining the detected vehicles by the proximity sensor which are notdetected by the light sensor as non-visible vehicles.

By comparing the vehicles detected on the one hand by the light sensors,such as a Lidar or camera, and on the other hand by the proximitysensors, it allows to easily distinguish the vehicles which are notvisible since they are not detected by the light sensors but only by theproximity sensors.

A second aspect of the disclosure relates to an advanced driverassistance system of a vehicle for detecting non-visible vehicles in thevehicle's environment, for implementing the method according to thefirst aspect, the system comprising at least one proximity sensorcomprising an emitter for emitting a proximity signal capable ofpropagating through the air along a non-linear path; a receiver in ascreening mode to screen and receive any incoming proximity signal; aprocessor for processing the received proximity signal to detect anon-visible vehicle; and a warning unit for warning a driver and/or theadvanced driver-assistance system of the detected non-visible vehicle.

The proximity sensor in some embodiments is an ultrasonic sensor, suchas a parking sensor. The system may include a plurality of proximitysensors arranged at the front, rear and sides of the vehicle.

A third aspect of the disclosure relates to a vehicle equipped with anadvanced driver assistance system according to the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present disclosure will appear moreclearly from the following detailed description of particularnon-limitative examples of the disclosure, illustrated by the appendeddrawings where:

FIG. 1A represents a driving scene according to a current situation;

FIG. 1B represents a similar driving scene as FIG. 1A implementing themethod for detecting non-visible vehicles;

FIG. 2 represents a flowchart of the method for detecting non-visiblevehicles; and

FIG. 3 represents a vehicle including a plurality of sensors useful inan example embodiment.

DETAILED DESCRIPTION

Before describing in more details one preferred method and systemaccording the present disclosure, one will understand that the presentdisclosure is perfectly transposable to other specific applications witha need to detect non-visible objects in a crowded environment.

FIG. 1A represents a driving scene according to the current situation.

A vehicle (A) moves on the main tracks of the roadway along a work zonedelimited by road work fences (10) regularly placed along the tracks. Onthe other side of the fences, there is a hidden lane for the vehicle (A)on which vehicles (B, C and D) are driving.

The vehicle (A) is arriving at a crossroad and intends to turn right. Atthe same time, vehicle (B) is driving forward without being seen by thevehicle (A). It results in a risk of collision between the vehicles (A)and (B).

Such driving scene would not be safer if vehicles (A) and (B) wereequipped with usual sensors like radar and camera as such devices wouldnot be able to detect vehicles through obstacles such as for instancework road fences or a parked vehicle. The delimitation of the risks arerepresented by two zones:

a “safe” zone represented by the region covered by a cloud of points;

a “non-visible” zone or “danger” zone represented by the hashed region.

FIG. 1B represents a similar driving scene as FIG. 1A implementing amethod to detect vehicles in the non-visible zone.

In the same manner, the vehicle (A) moves on the main track of theroadway along a work zone delimited by road work fences (10) regularlyplaced along the track. On the other side of the fences, there is ahidden lane for the vehicle (A) on which vehicles (B, C and D) aredriving. The vehicle (A) is arriving at a crossroad and intends to turnright. At the same time, vehicle (B) is driving forward without beingseen by the vehicle (A). It results in a risk of collision between thevehicles (A) and (B) where the safe zone and non-visible zone are thesame.

However, in the driving scene of FIG. 1B, both vehicles (A) and (B) areequipped with at least one proximity sensor. Both vehicles arepreferably by a plurality of ultrasonic sensors of the parking sensors.More preferably the vehicles can also be equipped with such sensors ontheir sides so as to be able to emit and receive signal from everywhere.

The emitters of the proximity sensors of the vehicle (A) emit aproximity signal (PSA) and the emitters of the proximity sensor of thevehicle (B) emit a proximity signal (PSB). In the case of a plurality ofsensors arranged on the front, the rear and preferably the sides of thevehicle, the proximity signals (PSA, PSB) are uniformly propagatedaround the vehicles (A, B). The proximity signals are preferablyultrasonic pulses periodically emitted.

The receivers of the proximity sensors of the vehicle (A) receive theincoming proximity signal (PSB) from vehicle (B) while the receivers ofthe proximity sensors of the vehicle (B) receive the incoming proximitysignal (PSA) from vehicle (A).

The received signals by each vehicle (A, respectively B) is thenprocessed to be able to detect a non-visible vehicle (B, respectively A)which is in the vehicle's environment (A, respectively B).

Although, it is not represented on FIG. 1B, the other non-visiblevehicles (C, D) may also be equipped with proximity sensors emittingproximity signals (PS_(C), PS_(D)) and be detected by the vehicle (A).

The detection of non-visible vehicles (e.g. B, C, D) may be done forinstance by analyzing the Doppler effect of the received proximitysignals to determine the distance and speed of these vehicles.

In other words, the emitter of the vehicle (B) emits ultrasonic pulses,whose wave front is spherical. The receiver of the vehicle (A) receivesthe wave with a delay, due to its propagation. Between two pulses, thevehicle (B) has moved with respect to the vehicle (A), and as a result,the spherical wave front does not have the same center. As a result whenapproaching the crossroad, as the emitter, i.e. vehicle (B), approachesthe receiver, i.e. vehicle (A), the waves arrive at a faster rate thanthe emission so that the period of the received pulses seems shorter,and therefore the frequency higher. On the other hand, when the emittermoves away from the receiver, the period seems longer, and therefore thefrequency smaller. A similar phenomenon occurs when the receiver movesrelative to the emitter, or when both move.

Further by using ultrasonic pulses modulated in amplitude as proximitysignals, the proximity signals may be further processed to determine anyspeed variation of the detected non-visible vehicles (e.g. B, C, D).Based on the detected and processed proximity signals, the vehicle isable to evaluate a risk of collision with any detected non-visiblevehicle.

Then the vehicle (A) may warn the driver and/or an advanceddriver-assistance system of vehicle (A) about the detected non-visiblevehicle, i.e. vehicle (B). And the vehicle (B) may warn the driverand/or an advanced driver-assistance system of vehicle (B) about thedetected non-visible vehicle, i.e. vehicle (A). Such warning reduces therisk of collision between both vehicles (A, B).

FIG. 2 represents a flowchart of the method for detecting non-visiblevehicles.

During a first step S1, the emitter of the proximity sensor emits aproximity signal. Preferably, the emitter generates a periodic pulse.The generated pulse has preferably a duration of 1 ms (millisecond) soas to reduce as far as possible the power consumption of the proximitysensor. The period between two pulses is 100 ms, i.e. 10 Hz frequency,which is a right compromise between power consumption and safe detectionof non-visible vehicles.

During a second step S2, the receiver of the proximity sensor is activein a “screening mode” (or “listening mode” for ultrasonic signals) to beable to detect any incoming proximity signal in the surroundings. Thereceiver is preferably switched on and become active only when theemitter is not generating a pulse. The listening mode is preferablyactive for 100 ms between two generated pulses by the emitter.Alternatively, it is possible to continuously let the receiver in thelistening mode even when the emitter generates a pulse to avoid anymisdetection of a non-visible vehicle which would be emittingsynchronously with the listening vehicle.

During the second step S2, the receiver in the listening mode detectswhether an incoming coming from a non-visible vehicle has been receivedor not. If no proximity signal has been received (alternative N), themethod loops on the first step. If a proximity signal has been received(alternative Y), the method loops also on the first step and processesthe received signal during a third step.

During the third step S3, a processor either of the proximity sensor orof an advanced driver-assistance system processes the received proximitysignal to detect any non-visible vehicle. Such detection may beperformed for example by using the Doppler effect and/or amplitudemodulation of the received signals. In this manner, the processor willbe able to determine the distance and the speed of the non-visiblevehicle.

During a fourth step S4, whenever a non-visible vehicle has beendetected, a warning message will inform the driver and/or the advanceddriver-assistance.

According to an example embodiment, each vehicle is further equippedwith at least one light sensor, such as a Lidar or a camera. During astep S_(A) running in parallel of the screening step, the light sensoris detecting visible vehicles in the vehicle's environment. During astep SB, the detected vehicles by the proximity sensor during step S3are compared with the detected vehicles by the light sensor during stepS_(A). During step S_(C), non-visible vehicles are determined as thevehicle which were not detected by the light sensor but only detected bythe proximity sensor. The results of step S_(C) are then used to performthe step S4.

FIG. 3 represents a vehicle 100 equipped with a plurality of ultrasonicsensors 210, 220 and 230. Preferably the sensors are (existing) parkingsensors 210 and 230 arranged on the front and rear of the vehicle. Morepreferably, it also comprises at least one ultrasonic sensor 220 on theside of the vehicle. Each sensor comprises an emitter and a receiver.

The vehicle 100 also comprises a processing unit, preferably included inan advanced driver-assistance system (ADAS) 300, for processing thesignals received by the sensors 210-230. More specifically, the advanceddriver assistance system is configured to detect non-visible vehicles inthe vehicle's environment.

For that purpose, at least one of the emitters of the sensors 210-230emits a proximity signal capable of propagating through the air along anon-linear path. At least one of the receivers of the sensors 210-230screens any incoming proximity signal from a non-visible vehicle in itsenvironment. Then, the ADAS processes the received proximity signal todetect the non-visible vehicle. When a non-visible vehicle is detected,a warning unit warns the driver and/or the ADAS of the presence of thedetected non-visible vehicle.

The ADAS 300 is connected with a steering unit 400 arranged to steer thevehicle, and a movement control unit 500 comprising a power unit,arranged to maintain or increase a vehicle speed and a braking unitarranged to stop the vehicle or to decrease the vehicle speed. Dependingon the evaluation of the risk of collision based on the warning message,the ADAS could assist the driver by adequately controlling the vehiclespeed and/or direction.

According to a preferred embodiment, the vehicle 100 is also equippedwith light sensors such as one or several cameras 610 to take a video ora continuous series of pictures when the vehicle is driven, or as analternative or in addition to the cameras, a 360° scanning unit 620, ora laser light scanning unit (LIDAR) for example. These light sensors maybe used to carry out the steps S_(A) to S_(C) described in relation withFIG. 2 .

It will be understood that various modifications and/or improvementsevident to those skilled in the art can be brought to the differentembodiments described in the present description without departing fromthe scope of the present disclosure defined by the accompanying claims.

The invention claimed is:
 1. A detection system, comprising: alight-based sensor that emits a first type of signal or radiation; adetector that detects a second type of signal or radiation that isdistinct from the first type of signal or radiation; and a processorthat is configured to determine when the detector receives the secondtype of signal or radiation from an object during a period when thedetector is not emitting the second type of signal or radiation,determine whether the light-based sensor detects the object, determinethat the object is outside of a field of view of the light-based sensorwhen the light-based sensor does not detect the object, and generate anoutput regarding the object.
 2. The detection system of claim 1, whereinthe detector is an ultrasound detector.
 3. The detection system of claim1, wherein the detection system is supported on a first vehicle, thedetector receives the second type of signal or radiation from a secondvehicle having a second detector that emits the second type of signal orradiation, and the output includes an indication of that the secondvehicle has been detected while the second vehicle may be outside afield of vision of a driver of the first vehicle.
 4. The detectionsystem of claim 3, wherein the detector comprises a plurality ofproximity sensors arranged at a front of the first vehicle, a rear ofthe first vehicle, and sides of the first vehicle and wherein at leastone of the proximity sensors is an ultrasonic sensor.
 5. The detectionsystem of claim 4, wherein the ultrasonic sensor is a parking sensor. 6.The detection system of claim 1, wherein the second type of signal orradiation has a non-linear wave front.
 7. The detection system of claim1, wherein the received second type of signal or radiation comprises aplurality of pulses, movement of the object relative to the detectorchanges a rate that the pulses are received by the detector, and theprocessor is configured to determine whether the object is approachingthe detector based on the rate.
 8. A detection method using alight-based sensor that emits a first type of signal or radiation and adetector that detects a second type of signal or radiation that isdistinct from the first type of signal or radiation, the methodcomprising: determining when the detector receives the second type ofsignal or radiation from an object during a period when the detector isnot emitting the second type of signal or radiation, determining whetherthe light-based sensor detects the object, determining that the objectis outside of a field of view of the light-based sensor when thelight-based sensor does not detect the object, and generating an outputregarding the object.
 9. The method of claim 8, wherein the detector isan ultrasound detector.
 10. The method of claim 8, wherein thelight-based sensor and the detector are supported on a first vehicle,the detector receives the second type of signal or radiation from asecond vehicle having a second detector that emits the second type ofsignal or radiation, and the output includes an indication of that thesecond vehicle has been detected while the second vehicle may be outsidea field of vision of a driver of the first vehicle.
 11. The method ofclaim 9, wherein the detector comprises a plurality of proximity sensorsarranged at a front of the first vehicle, a rear of the first vehicle,and sides of the first vehicle and wherein at least one of the proximitysensors is an ultrasonic sensor.
 12. The method of claim 11, wherein theultrasonic sensor is a parking sensor.
 13. The method of claim 8,wherein the second type of signal or radiation has a non-linear wavefront.
 14. The method of claim 8, wherein the second type of signal orradiation comprises a plurality of pulses, movement of the objectrelative to the detector changes a rate that the pulses are received bythe detector, and the method comprises determining whether the object isapproaching the detector based on the rate.